1. Field of the Invention
The present invention relates to a semiconductor device inspecting apparatus which cuts a semiconductor device and observes a cut cross section by an electron microscope, thereby analyzing a defective portion and observing a structure, etc. More particularly, the present invention relates to a semiconductor device inspecting apparatus capable of generating a sharp cut cross section.
2. Description of the Prior Art
Conventionally, as an apparatus for analyzing a defective portion in a developing process of a semiconductor device (LSI and the like), there is a known semiconductor device inspecting apparatus comprising a combination of an FIB (Focused Ion Beam) apparatus and a scanning electron microscope (SEM: Scanning Electron Microscope) (see Japanese Patent Application Laid-open No. H11-273613 for example).
According to this inspecting apparatus, a surface of the semiconductor device such as a semiconductor wafer is irradiated with FIB, thereby forming a fine groove or hole of submicron to micron size in the surface, or cutting the wafer, and the cross section is observed by the SEM, and analysis of defective portion or analysis by high resolution observation can be carried out.
There is also a known semiconductor device inspecting apparatus comprising a combination of the FIB apparatus and a transmission electron microscope (TEM: Transmission Electron Microscope). With this inspecting apparatus also, a semiconductor device such as a semiconductor wafer is irradiated with FIB to form a thin film sample, the sample is observed by the TEM, and evaluation of the semiconductor device or analysis of the defective portion can be carried out.
According to the above conventional semiconductor device inspecting apparatus, however, since the precision of working (such as cutting) by the FIB is affected by the atmosphere in a chamber (e.g., a temperature, a pressure) and the like, a worked surface (cut surface) does not appear sharply. Further, experience is required for working a wafer by the FIB in some cases. Furthermore, it takes time to work using the FIB and as a result, efficiency of the evaluation and analysis of the semiconductor device are inferior.
Further, according to the above-described semiconductor device inspecting apparatus, since a beam generating source of the FIB apparatus must be disposed in the chamber, a structure of the entire apparatus becomes complicated, and a producing cost is increased.
In addition, during driving operation of the FIB apparatus, since the sample (semiconductor device) is irradiated with ion beams, observation can not be carried out in real time using the SEM while working a fine defective portion using the FIB in some cases.
Further, according to the FIB apparatus, although the output is the same, a cutting depth is affected by the atmosphere in the chamber, characteristics of electromagnetic lens and the like, it is not easy to adjust the cutting depth.
It is a first object of the present invention to provide a semiconductor device inspecting apparatus capable of inspecting a semiconductor device precisely by forming a sharp working surface.
It is a second object of the present invention to provide a semiconductor device inspecting apparatus capable of enhancing the inspecting efficiency by working a semiconductor device within a short time.
It is a third object of the present invention to provide a semiconductor device inspecting apparatus in which its structure is not complicated.
It is a fourth object of the present invention to provide a semiconductor device inspecting apparatus capable of cutting and observing a working surface at the same time.
It is a fifth object of the present invention to provide a semiconductor device inspecting apparatus capable of always cutting uniformly without being affected by atmosphere in the chamber so much.
The present invention provides a semiconductor device inspecting apparatus comprising a stage disposed in a chamber on which a semiconductor device such as an LSI is set, a femtosecond laser apparatus for generating laser beams which cut the semiconductor device, and an electron microscope for observing a cut surface of the semiconductor device which was cut by the laser beams.
As the femtosecond laser apparatus, laser beams (titanium sapphire laser) of several tens to several hundreds fsec time width is used. xe2x80x9cCuttingxe2x80x9d in this invention includes formation of a groove and a hole in a surface of a semiconductor device such as an LSI, and cutting of the semiconductor device.
The femtosecond laser apparatus is used in the present invention. Therefore, it is possible to cut the semiconductor device at high speed, to cut the semiconductor device deeply, to make the depth uniformly, and to form a groove whose depth is changed at a predetermined-distance by changing a focus, distance of the laser beams during scanning. Further, since one dimensional or two dimensional cutting line can be controlled by a mirror provided in a laser optical path, it is possible to extremely shorten time required for cutting.
It is possible to cut the semiconductor device and to observe the working surface at the same time, and influence of atmosphere in the chamber is small, and the semiconductor device can always be cut uniformly.
The semiconductor device inspecting apparatus of the present invention uses a scanning electron microscope (SEM) or a transmission electron microscope (TEM).
In the semiconductor device inspecting apparatus of the invention, since the femtosecond laser apparatus is used as a laser beam source (i.e., an ion beam laser is not used), at least the laser generating section can be provided outside the chamber. With this feature, a structure of the semiconductor device inspecting apparatus is not complicated.